Also known as: Hansen's disease
The primary diagnosis driving the entire episode. A 12-year-old boy presents with fever, respiratory symptoms, and a rash. The team discovers he contracted leprosy from his father, who had visited an Indian ashram years earlier. The leprosy weakened his immune system, making him vulnerable to anthrax, and the antibiotic treatment triggered a severe inflammatory reaction as his body attacked the dead leprosy bacteria.
Secondary major diagnosis that creates diagnostic confusion. Gabe contracted anthrax from animal hair insulation in an abandoned house attic. The anthrax caused respiratory symptoms and a characteristic rash with necrosis. The case is complicated because the leprosy made him vulnerable to the anthrax infection.
Also known as: Lung infection
Initial presenting complaint that brings Gabe to the hospital. He has fever, chest congestion, productive cough with green sputum, and breathing pain. The pneumonia is later revealed to be caused by the anthrax infection rather than typical bacterial pneumonia.
Also known as: Nerve compression in wrist
Misdiagnosis in Gabe's father. He was previously diagnosed and surgically treated for carpal tunnel syndrome, but House realizes the wrist pain was actually caused by ulnar nerve damage from undiagnosed leprosy contracted in India decades earlier.
Also known as: Lung cancer
Stage IV lung cancer in Chase's father, who traveled from Australia to receive treatment at Sloan-Kettering. He has three months to live. House deduces this from a radiation tattoo marker and the father's macrobiotic diet. This subplot drives the emotional arc between Chase and his father.